The American Society of Primatologists (ASP) is a scientific organization whose purpose is to encourage the discovery, exchange and dissemination of information regarding nonhuman primates, including their biology, care, and conservation. Dr. Fragaszy, ASP President, asked ASP’s Primate Care Committee to provide a statement related to implementing the recommendations of the IOM committee. Please see the attached file for our complete statement and the references cited.
Defining an Ethologically Appropriate Physical Environment for Chimpanzees
Based on our review of the scientific literature related to chimpanzees, there is a convergence of thinking from scientists working with chimpanzees in laboratories, zoos, and in the field, on several major features of the physical environment needed by captive chimpanzees. We propose that the environmental features that are repeatedly mentioned as important by scientists in these various settings, are the ones that should be incorporated into every ethologically appropriate environment for captive chimpanzees.
1) Foraging behavior. Wild chimpanzees spend the largest portion of their waking hours feeding and foraging, so captive environments should allow for multiple opportunities each day to search for, process and acquire a wide variety of foods (Pruetz & McGrew, 2001; Bloomsmith & Else, 2005).
2) Nesting behavior. Wild chimpanzees build nests made from branches and leaves, and spend about 12 of every 24 hours in those nests, including sleeping in the nests at night, and resting in them during the day (Furth & McGrew, 1998; Hiraiwa-Hasegawa, 1989). Captive environments should include elevated platforms or other comfortable, stable spaces for nesting (Coe et al., 2001). In addition, appropriate soft, flexible and safe materials (e.g., browse, hay, excelsior, blankets, branches) should be provided daily for chimpanzees to build nests.
3) Traveling, climbing and brachiating. Wild chimpanzees spend about 10-20% of their waking time traveling (Boesch & Boesch, 2000; Ghiglieri, 1985; Wrangham, 1977). Therefore, ethologically appropriate environments for chimpanzees should allow traveling, climbing, and brachiating.
4) Problem-solving behaviors. All populations of wild chimpanzees studied use tools to solve problems in some form or fashion (Wrangham, 1992), so ethologically appropriate environments for captive chimpanzees should encourage the use of tools and other means of solving problems.
Defining an Ethologically Appropriate Social Environment for Chimpanzees1) Social housing is the foundation for captive chimpanzee welfare (Pruetz & McGrew, 2001; Wrangham, 1992; AZA Ape TAG, 2010; Bloomsmith & Else, 2005; Brent, 2001). An ethologically appropriate environment must support the social needs of captive chimpanzees and include conspecific social partners. 2) Since chimpanzees show complex social interactions and multi-animal interactions (e.g., alliances, consolation), we propose a minimum group size of three chimpanzees, to allow such interactions. 3) We recommend group sizes larger than three, as larger groups more closely approximate the size of wild chimpanzee communities. These groups should contain multiple adult members of both sexes to model the fission/fusion nature of wild chimpanzee groups (Goodall, 1986), and fulfill the Pruetz & McGrew (2001) recommendation that chimpanzees interact with a wide range of social partners.4) Any research that requires extensive periods of single housing cannot be deemed acceptable under the criteria of ethologically appropriate social environments. A more difficult question is whether brief periods of single housing might be allowable. For example, the IOM Committee report endorsed the value of neuroimaging studies with chimpanzees, but some of these studies (e.g., PET imaging) involve a period of single housing. We propose that periods of single housing of up to 24-hours each in duration, no more than four times per year, may be deemed acceptable for research purposes if extremely well justified. 5) Requiring housing with conspecifics during research periods has implications for studies of infectious diseases using chimpanzees (e.g., hepatitis). Additional chimpanzees will be exposed to infectious agents through their social partners and could become infected themselves.
Defining “Acquiescent Chimpanzees”Chimpanzees can be trained using positive reinforcement techniques to cooperate with a variety of husbandry, veterinary and research procedures (Bloomsmith et al., 1998; Bloomsmith et al., 2006; Coleman et al., 2008; Laule et al., 1996; Laule et al., 2003; Perlman et al, 2010). Positive reinforcement training relies on the voluntary participation of the chimpanzees—there is no consequence to them if they decide to not participate, other than the failure to earn additional rewards. We propose that positive reinforcement training is the optimal methodology to achieve acquiescence with research procedures.
1) Positive reinforcement training reduces distress experienced by chimpanzees (Lambeth et al., 2006; Pomerantz & Terkel, 2009).
2) To train chimpanzees who are acquiescent, we propose that the training methods should follow these criteria:
3) Requiring research procedures to be conducted with acquiescent chimpanzees may place practical limits on the frequency of certain research procedures, and will increase the cost of conducting chimpanzee research.